Quarter	Percent
1999-04-01	50.4
1999-07-01	47.7
1999-10-01	49.3
2000-01-01	49.5
2000-04-01	49
2000-07-01	46.8
2000-10-01	48.3
2001-01-01	48.6
2001-04-01	48.6
2001-07-01	45.9
2001-10-01	47.5
2002-01-01	47.3
2002-04-01	47.3
2002-07-01	45.8
2002-10-01	47.2
2003-01-01	47.2
2003-04-01	47
2003-07-01	45.1
2003-10-01	46.3
2004-01-01	46.6
2004-04-01	46.6
2004-07-01	44.9
2004-10-01	45.1
2005-01-01	45
2005-04-01	44.5
2005-07-01	42.9
2005-10-01	43.8
2006-01-01	43.7
2006-04-01	43.3
2006-07-01	41.6
2006-10-01	42.7
2007-01-01	39.4
2007-04-01	38.5
2007-07-01	37.9
2007-10-01	38.9
2008-01-01	39.1
2008-04-01	38.8
2008-07-01	38.0
2008-10-01	39.5
2009-01-01	40.0
2009-04-01	39.2
2009-07-01	38.9
2009-10-01	40.3
2010-01-01	41.0
2010-04-01	40.0
2010-07-01	40.1
2010-10-01	40.7
2011-01-01	41.3
2011-04-01	40.2
2011-07-01	40.4
2011-10-01	40.8
2012-01-01	41.0
2012-04-01	40.6
2012-07-01	40.5
2012-10-01	41.2
2013-01-01	41.0
2013-04-01	39.7
2013-07-01	39.7
2013-10-01	40.5
2014-01-01	41.0
2014-04-01	40.7
2014-07-01	39.8
2014-10-01	40.7
2015-01-01	41.3
2015-04-01	40.4
2015-07-01	40.1
2015-10-01	40.4
2016-01-01	40.8
2016-04-01	39.2
2016-07-01	39.2
2016-10-01	39.8
2017-01-01	40.0
2017-04-01	39.8
2017-07-01	39.4
2017-10-01	39.3
2018-01-01	40.1
2018-04-01	38.8